Integrated circuits sometimes undergo attacks from pirates aiming at determining the structure of the circuit, at modifying the operation thereof, or at extracting confidential data therefrom. An attack may be carried out from the rear surface of a circuit provided at its front surface with conductive tracks and with components such as capacitors, diodes, or transistors. During the attack, a portion of the rear surface is first etched. From this etched portion, cavities having a width of a few microns are for example formed by an ion beam and extend towards the upper surface all the way to the components or to the conductive tracks. Electric contacts with the components or the tracks are then created in the cavities, and pirates use these contacts to analyze the circuit in operation.
It is desirable to have integrated circuits protected against this type of attack, known devices having various disadvantages and implementation issues.